edit

lib/Base.php

@@ -147,6 +147,6 @@ class Base
     {
         $len = isset($this->config['code_length']) ? $this->config['code_length'] : 4;
         $type = isset($this->config['code_type']) ? $this->config['code_type'] : 4;
-        return Dever::rand($len, $type);
+        return Dever::rand($len, $type - 1);
     }
 }